Electronic paper (or e-paper) is commonly used for e-reader devices because it only requires power to change the image displayed and does not require continuous power to maintain the display in between. The electronic paper can therefore hold static images or text for long periods of time (e.g. from several minutes to several hours and even several days, months or years in some examples) without requiring significant power (e.g. without any power supply or with only minimal power consumption). There are a number of different technologies which are used to provide the display, including electrophoretic displays, electrochromic and electro-wetting displays. Many types of electronic paper display are also referred to as ‘bi-stable’ displays because they use a mechanism in which a pixel can move between stable states (e.g. a black state and a white state) when powered but holds its state when power is removed.